Victorian Opal & Seed Pearls Stick Pin

For sale is this extraordinary, circa 1880's stickpin set with an oval 6mm x 8mm fiery opal and eight tiny seed pearls. The head of the pin measures 1/2" long and is being sold as gold filled simply because I do not want to cause any damage doing an acid test. The pin is nickel plated. Absolutely no damage or repairs. Opal appears milky and thin, but it is really blue and fiery in person.